Print
The salmon's story
Migrating salmon fight the currents to reach their breeding grounds
Female salmon lay their eggs upstream. When the eggs hatch, the young salmon (called fry) drift slowly downstream. Most die, but the survivors gradually get bigger. Once they reach the sea, after about two years, they set off on a journey of thousands of kilometres to reach their ocean feeding grounds. Here they continue to grow, doubling their weight each year as they feed on smaller fish.
After about four years, when the salmon have grown into strong adult fish, weighing 10 kg or more. They swim back across the ocean to the mouth of the river where they were born. Here they wait for a strong enough water flow, before heading upriver.
By now, the males are sporting their bright breeding colours. Nothing but death can stop the salmon migrating upstream; they will fight the fiercest currents and even jump up waterfalls.
By October, the adult salmon have reached the place where they were born. Here they mate and the females lay their eggs in a shallow scrape in the riverbed. This is called spawning. After spawning, 95% of all adults die. But those that survive head back out to sea to start their journey all over again. Meanwhile, in spring, their eggs hatch and a new generation of salmon prepares to start the great adventure.
The epic journey of the salmon also causes other animals to migrate. In Alaska, grizzly bears and bald eagles gather each year at salmon spawning sites upriver. The huge numbers of exhausted and dying fish provide a welcome feast for these big predators. The bears eat as much as they can in preparation for their winter hibernation.
Last modified: 11 January 2005